ch 6 Flashcards
promoters
specific DNA sequences
activators
transcription factors
bind DNA and activate transcription
what are transcription factors
proteins that help control the process of transcription
mechanisms of activators
recruits RNA polymerase
loosening chromatin
recruiting coactivators
coactivators
other proteins that help initiate transcription
they recruit RNA polymerase
repressors
proteins that induce transcription
mechanisms of repressors
prevent activators from binding
closing chromatin
recruits corepressors
corepressors
proteins that help prevent transcription
enhancers
DNA regions FURTHER AWAY from transcription start site
brought near promoter using DNA looping
T/F: there are multiple enhancers per gene
true
sillencers
inhibitory
distant DNA sites that inhibit transcription
recruit repressive transcription factors
heterochromatin
tightly compacted chromatin
euchromatin
loosely compacted chromatin
what controls chromatin compaction
chemical modifications of DNA bases
chemical modifications of some histones
DNA methylation
methyl groups added to Cytosine
happens mostly at gene promoter
reduces expression of gene region
T/F: methyl groups are nonpolar and hydrophobic
true!!!
demethylase
enzymes that remove methyl groups
reactivates gene region
writers
enzymes that add methyl groups to DNA
readers
proteins that binds to histones and influences transcription
erasers
proteins that remove histone modifications
what are the two main RNA categories
messenger RNAs
noncoding RNAs
microRNAs
small RNAs that regulate translation
bind to mRNA and prevent genes from being translated into proteins
RISC
RNA-induced silencing complex
recruits proteins to degrade mRNA or stop translation from starting
T/F: miRNA is complementary to the target mRNA
true
lncRNA
long noncoding RNA
more than 200 nucleotides long
diverse functions
serves as macromolecular scaffold
bind DNA based on complementary base pairing
macromolecular scaffold
organize proteins around itself to make a complex
miRNA sponging
lncRNAs contain miRNA binding site
prevents miRNA from binding to mRNA
influences translation of those mRNAs
transposons
jumping genes
genes that move locations in genome
two types
-DNA transposons
-retrotransposons
DNA transposons
cut and paste
DNA cut out and placed elsewhere in genome
retrotransposons
copy and paste
transcribed into RNA
RNA is reverse transcribed into DNA
DNA inserted into other DNA regions
